Ozone hole modest despite optimum conditions for depletion, claim scientists

Although colder-than-average temperatures in the Antarctic stratosphere created ideal conditions for destroying ozone in 2018, scientists from the NASA and National Oceanic Atmospheric Administration (NOAA) have revealed.

The findings showed that the ozone hole in the upper atmosphere was slightly lower than the average size in 2018.

"This year's colder temperatures would have been much greater than 2000 years ago," said Paul A. Newman, Chief Scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland .

According to NASA, the annual ozone hole reached an average area of ​​coverage of 22.9 square kilometers in 2018.

NOAA scientists said colder temperatures in 2018 for near-complete elimination of ozone in a deep, 5km layer over the South Pole. This layer is where the active chemical depletion of ozone occurs on polar stratospheric clouds.

"Even with this year's optimum conditions, we are expecting more chlorine concentrations than we are seeing in the stratosphere," added NOAA scientist Bryan Johnson.

Nations of the world began to use ozone-depleting substances in 1987 under the umbrella of the Montreal Protocol.

The 2018 ozone hole was strongly influenced by a stable and cold Antarctic vortex – the stratospheric low-pressure system that flows into the atmosphere above Antarctica.

In 2016 and 2017, warmer temperatures in September limited the formation of polar stratospheric clouds and slowed ozone hole growth. In 2017, the ozone hole reached a size of 19.7 square km before starting to recover.

In 2016, the hole grew to 20.7 square kilometers.

However, the current ozone hole is still broadly compared to the 1980s, when the depletion of the ozone layer was first detected. Atmospheric levels of man-made ozone-depleting substances increased up to the year 2000.

Since then, they have slowly decreased but remain high enough to produce significant ozone loss.